Pipe such as cast iron, clay or ductile metal pipe has been used for connecting homes and creating networks for utilities such as water, sewer, or gas, etc. As the pipe becomes old, it may crack or break, necessitating replacement of the pipe.
A technique know as pipe bursting is currently used as a convenient method to replace underground pipe without the need to dig up the pipe to be replaced. A pipe breaking device, commonly called an expander or a mole, is pulled or pushed through the existing pipe while it is still underground. The expander is designed to break, or burst the pipe, and at the same time to expand the broken pieces of the pipe into the surrounding soil. The expansion of the broken pipe allows the expander to pull a replacement pipe into place. Alternatively, some methods use the expander to merely pull a smaller diameter pipe into place inside the existing pipe, however, this method restricts the flow in the replaced pipe due to the smaller diameter of the replacement or liner pipe. The pipe bursting, or lining technique has typically been employed on large diameter pipe such as water or sewer main lines. Due to the size of pipe in these types of replacements, the equipment used for pulling or pushing the expander through the pipe requires a great deal of force. As a result, common equipment in the industry for pulling or pushing the expander is relatively large and expensive such as an above ground winch and pulley system. These larger scale methods also commonly require a large access pit to be excavated on at least one end of the pipe to be replaced.
More recently, the technique of pipe bursting has been employed for smaller diameter pipe such as for lateral lines. Smaller branch pipes from a large water or sewer, etc. main line are commonly referred to as lateral lines. Replacement of smaller lateral lines is typically a lower cost job than main lines, and due to the lower profit possibilities, these jobs are frequently left to smaller contractors.
A problem arises for the smaller contractors who wish to use the pipe bursting technique for lateral line replacement. The common industry equipment for drawing or pushing the expanders through the pipe is too expensive to purchase or lease relative to the smaller profits from lateral line replacement.
What is needed is a cable pulling device that is smaller, less expensive, and easy to use to be practical for lateral line replacement.